Citrate silicone polyesters

ABSTRACT

The present invention is directed to a series of polymeric citrate esters that have unique liquidity, and outstanding feel when applied to the skin. The polymers of the present invention are made by polymerizing citrate mono and di fatty esters with a hydroxypropyl functional silicone to provide a polymer with a very low surface tension and outstanding skin feel.

FIELD OF THE INVENTION

The present invention is directed to a series of polymeric citrate esters that have unique liquidity, and outstanding feel when applied to the skin.

The polymers of the present invention are made by polymerizing citrate mono and di fatty esters with a hydroxypropyl functional silicone to provide a polymer with a very low surface tension and outstanding skin feel.

One of the surprising aspects of the present invention is that the silicone is insoluble when added to the performed esters, but upon reaction clears and becomes soluble and alters the properties of the esters giving silicone resin like feel.

BACKGROUND OF THE INVENTION

Citric acid is a common material of natural origin. The CAS Registry Number: 77-92-9, the CA Index Name: 1,2,3-Propanetricarboxylic acid, 2-hydroxy-

Citric acid is made by fermentation, using cultures of Aspergillus niger are fed on a sucrose or glucose-containing medium

Citric acid is one of a series of compounds involved in the physiological oxidation of fats, proteins, and carbohydrates to carbon dioxide and water. This series of chemical reactions is central to nearly all metabolic reactions, and is the source of two-thirds of the food-derived energy in higher organisms. Krebs received the 1953 Nobel Prize in Physiology or Medicine for the discovery. The series of reactions is known by various names, including the citric acid cycle, the Krebs cycle, and the tricarboxylic acid cycle

Citrate esters are known. They conform to the following structure:

The esters are made by the reaction of fatty alcohols with citric acid.

U.S. Pat. No. 4,292,192 issued to Hooper, et al. teaches that Detergent bars for personal washing are given a deodorant property by including an ester of citric acid. The ester may be an acetyl derivative. The amount of ester used will be in the range of from about 0.3% to about 3%. Examples of the esters are triethyl citrate and acetyl tributyl citrate.

U.S. Pat. No. 2,122,716 describes long chain esters of citric acid, e.g., tridodecyl citrate, which have been used as plasticizers for resinous compositions.

U.S. Pat. Nos. 3,239,555 and 3,241,992 disclose bis-citric acid esters made by esterifying the acid groups with C1 to C18 alcohols and coupling the esters with dibasic acids. Such esters are useful as plasticizers for plastics.

U.S. Pat. No. 3,251,792, the acid groups of citric acid are esterified with alkyl, aryl, cycloalkyl and haloaryl alcohols and the hydroxyl group is esterified with a carbonyl compound. Such compounds are used as stabilizers for polypropylene.

U.S. Pat. No. 5,089,658 issued Feb. 18, 1992 to Elmore et al, is directed to citric acid esters. In one aspect, this invention pertains to citric acid esters, which contain at least one primary or secondary hydroxyl group. In another aspect, this invention relates to citric acid esters, which are reactive diluents. In still another aspect, this invention pertains to citric esters, which are pigment dispersants. The citric ester compositions of this invention are useful as reactive diluents for high solids thermosetting coating composition and as pigment dispersants for use in thermosetting coatings

U.S. Pat. No. 4,868,236 to O'Lenick discloses a guerbet citric ester and polymers thereof useful in plastic lubrication.

None of these patents provide polyester derivatives of mixed fatty esters of citrate as envisioned by the present invention.

THE INVENTION Objective of the Invention

The present invention has as its objective a series of citrate polyesters that have based upon fatty and guerbet alcohols reacted with citric acid, and crosslinked by specific silicone compounds that have terminal hydroxypropyl groups. The incorporation of these groups into the polymer gives them siliphilic properties and makes the surface tension, spreading and skin feel more like silicone than fatty esters. These polymers have a very low viscosity when one considers the molecular weight, and are ideally suited to personal care applications due to their unique feel.

The present invention also has an objective a process for treating hair and skin with the citrate/silicone polyesters of the present invention.

Other objectives will become clear as one reads the specification and claims herein.

SUMMARY OF THE INVENTION

The present invention discloses a polyester made by the reaction of a mixture of guerbet alcohols reacted with citric acid and a diol crosslinker.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a polyester that conforms to the following structure:

R¹ is selected from the group consisting of CH₃(CH₂)_(n)—;

and mixtures thereof; R² is

a is an integer ranging from 0 to 25.

Another aspect of the present invention is a process for conditioning hair and skin which comprises contacting the hair or skin with an effective conditioning concentration of a polyester that conforms to the following structure:

R¹ is selected from the group consisting of CH₃(CH₂)_(n)—;

and mixtures thereof; n is an integer ranging from 7 to 21; R² is

b is an integer ranging from 0 to 25.

In a preferred embodiment said effective conditioning concentration ranges from 0.1% to 20% by weight.

The products of the present invention are made by the esterification reaction of:

(a) citric acid conforming to the following structure:

(b) an alcohol selected from the group consisting of CH₃(CH₂)_(n)—OH;

and mixtures thereof; n is an integer ranging from 7 to 21; and (c) a terminal hydroxypropyl silicone conforming to the following structure:

b is an integer ranging from 0 to 25.

Another aspect of the present invention is a process for conditioning hair and skin which comprises contacting the hair or skin with an effective conditioning concentration of a polyester made by the esterification reaction of:

(a) citric acid conforming to the following structure:

(b) an alcohol selected from the group consisting of CH₃(CH₂)_(n)—OH;

and mixtures thereof; and (c) a terminal hydroxypropyl silicone conforming to the following structure:

b is an integer ranging from 0 to 25.

PREFERRED EMBODIMENTS

In a preferred embodiment a is an integer ranging from 1 to 20.

In a preferred embodiment a is an integer ranging from 3 to 10.

In a preferred embodiment a is 10.

In a preferred embodiment a is 15.

In a preferred embodiment b is 0.

In a preferred embodiment b is 10.

In a preferred embodiment b is 15.

In a preferred embodiment b is 20.

In a preferred embodiment b is 25.

EXAMPLES Example 1 Citric Acid

Citrate is an item of commerce commercially available from a variety of sources including Pfizer. It conforms to the following structure:

Examples 2-5 Fatty Alcohols

The fatty alcohols useful for the preparation of compounds of the present invention conform to the following structure: CH₃(CH₂)_(n)—OH; n is an integer ranging from 7 to 21;

Example n 2 7 3 11 4 17 5 21

Example 6 Octyldodecanol

Octyldodecanol is a Guerbet alcohol commercially available from a variety of sources including Cognis.

Hydroxypopyl Terminal Silicones Examples 7-11

The hydroxypropyl silicones of the present invention are commercially available from Siltech LLC and are sold under the Silmer OH trade name. They conform to the following structure;

b is an integer ranging from 0 to 25.

Example b 7 0 8 10 9 15 10 20 11 25

General Procedure

To a suitable reactor equipped with heating and an ability to distill off water is added the specified number of grams of citrate acid (Example 1), finally is added the specified number of grams of the fatty alcohol (Examples 2-6). The reaction mass is heated to 150-160° C. and water is distilled off. As the reaction proceeds, the batch clears and free citric acid is reacted out. The reaction mass is kept at this temperature until the acid value becomes vanishingly low. Next is added the specified number of grams of the specified hydroxypropyl (Examples 7-11). The reaction mass is heated to 180-190° C. and water is distilled off. The reaction mass is kept at this temperature until the acid value becomes vanishingly low. The reaction mass is cooled and used without additional purification.

Citric Acid Alcohol Silicone Example 1 Example 2-6 Example 7-11 Example Grams Ex Grams Ex Grams a value 12 34.2 2 61.4 7 44.0 20 13 44.0 3 31.0 8 25.0 5 14 37.6 4 44.0 9 18.4 10 15 30.3 5 38.0 10 31.7 5 16 30.0 6 33.5 11 36.5 5 17 23.1 2 41.3 11 35.6 20 18 33.0 3 40.0 10 27.0 7 19 38.3 4 40.0 8 21.7 5 20 34.5 5 49.0 9 16.5 10 21 44.4 6 51.0 7 4.6 3 22 37.2 4 13.0 8 21.5 5 6 28.5 23 33.1 5 20.6 9 27.2 5 6 19.1 24 43.0 6 52.7 7 3.0 10 2 1.3 25 33.2 3 21.0 9 26.8 5 6 19.0

Products that are of the present invention were low order liquids that range from very dry easily spread (a is 1-10), to medium viscosity (a is 12-15), to viscous liquids with a lot of cushion and play tome.

The compounds are of exceptional interest in the personal care applications where gloss, rheology that accommodates spreading and odor are critical.

The higher the “b” value the greater the silicone feel. Low values of “b” result in products with an oily type feel. As the value of “b” increases the product becomes dry feeling leaving no residue on the skin, with the optimum being b is 10. As the number increases above 10 the products become greasier. As the “b” value continues to increase a clear reaction product will not occur.

While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth hereinabove but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains. 

1. A polyester made by the esterification reaction of: (a) citric acid conforming to the following structure:

(b) an alcohol selected from the group consisting of CH₃(CH₂)_(n)—OH;

and mixtures thereof; n is an integer ranging from 7 to 21; and (c) a terminal hydroxypropyl silicone conforming to the following structure:

b is an integer ranging from 0 to
 25. 2. A polyester of claim 1 wherein n is
 7. 3. A polyester of claim 1 wherein n is
 11. 4. A polyester of claim 1 wherein n is
 17. 5. A polyester of claim 1 wherein n is
 21. 6. A polyester of claim 1 wherein b is
 0. 7. A polyester of claim 1 wherein b is
 10. 8. A polyester of claim 1 wherein b is
 20. 9. A polyester of claim 1 wherein b is
 15. 10. A process for conditioning hair and skin which comprises contacting the hair or skin with an effective conditioning concentration of a polyester made by the esterification reaction of: (a) citric acid conforming to the following structure:

(b) an alcohol selected from the group consisting of CH₃(CH₂)_(n)—OH;

and mixtures thereof; and (c) a terminal hydroxypropyl silicone conforming to the following structure:

b is an integer ranging from 0 to
 25. 11. A process of claim 10 wherein said effective conditioning concentration ranges from 0.1% to 20% by weight.
 12. A process of claim 11 wherein n is
 7. 13. A process of claim 11 wherein n is
 11. 14. A process of claim 11 wherein n is
 17. 15. A process of claim 11 wherein n is
 21. 16. A process of claim 11 wherein b is
 0. 17. A process of claim 11 wherein b is
 10. 18. A process of claim 11 wherein b is
 20. 19. A process of claim 11 wherein b is
 15. 